Qinetiq, the former government-owned defence research and technology group which controversially floated on the stock market earlier this year, said yesterday it could spend up to £250m to expand its US business.

The company, which listed in February with a value of £1.3bn, said it wanted to increase the proportion of group sales generated in the North American market from a third to more than a half in the next four to five years.

Qinetiq has so far spent £300m buying up US companies, and Graham Love, its chief executive, said there were further acquisitions in the pipeline.

He was speaking as Qinetiq unveiled its maiden results as a publicly-quoted company. Underlying pre-tax profits for the year to the end of March rose 38 per cent to £91m. Sales were 23 per cent higher at £1.052bn.

Although the figures were in line with expectations, they failed to stop Qinetiq shares slipping further.

They closed 2 per cent down at 170.5p, having been floated at 200p amid a storm of protest in some quarters that small shareholders had been frozen out of the privatisation.